The invention relates to a method for harvesting threshed crops according to the preamble of claim 1. The invention also includes a device for harvesting threshed crops.
Within the context of the invention, the term harvest includes all those method steps necessary for harvesting agricultural plants and crops. The threshed crops, in particular grain crops in form of grain, are composed substantially of grain, chaff and straw.
While the straw and the grain are supplied to their conventional use, the recovery of chaff as a material component of the cereal crop has decreased in importance in Europe. Even with the use of stationary automatic combine harvesters, the chaff was part of the harvest of the entire plant and could be captured and used separately. When the threshing operation was moved from the farm to the field through the use of mobile combine harvesters, this could initially still be mastered at low travel speeds and small cutting assembly widths with chaff bags and later with changeable chaff vehicles coupled to the combine harvester. The very high-volume chaff production with the introduction of the combine harvesters eliminated the recovery, in particular from the mid-1960s on, because the transfer to parallel moving high-volume trailers was inefficient. There is presently the problem in that modern combine harvesters can distribute the chaff uniformly across the cutting width only through additional energy consumption.
DE 35 44 157 C1 discloses a device for combine harvesters for distributing the chaff. The device consists of rotating blades and of a support frame with a rear cover plate in which two rotors with at least two turbine-like blades driven in opposite directions are supported next to each other for rotation about mutually parallel axes, wherein the frame can be movably guided on two supports and locked in position. The invention is characterized in that the supports are tiltably supported at one end on sleds which are adjustably guided in rails connected with the combine harvester, and that the other ends of the supports can be fixed in different tilt positions.
DE 28 37 814 A1 discloses a combine harvester for harvesting grain at the front end of the combine harvester, threshing the harvested grain and discharging the straw and the chaff from a straw shaker or a screen disposed at the rear end of the combine harvester. This invention is characterized in that a collection hopper is provided for receiving the straw or the chaff, with a conveyor belt discharging the straw and the chaff at a certain distance from the collection hopper being pivotally arranged at the output end of the collection hopper.
U.S. Pat. No. 7,651,391 B2 describes a method and a device for directly recovering biomass produced during threshing in the field.
Furthermore, a superstructure silo arranged at the rear end of the combine harvester for receiving chaff has been disclosed by the company Thierart, 08300 Le Châtelet-sur-Retourne, France. The silo which consists of low-weight canvas attains a volume of up to 16 m3. However, because of the different required transfer and transport solutions for grain and chaff, the attainable throughput capacity of the combine harvester designed for grain harvest is reduced. The solution is suitable for a locally important demand for feed chaff in limited transport quantities and also for smaller acreage with less time pressure in the harvesting technology.
Another solution described in CA 2,180,691 A is the common capture of grain and chaff in a combine harvester silo without cleaning device. This solution is not suitable for high yields. Additional costs are incurred for transport, without being able to eliminate the recovery of straw which is also required.
The aforedescribed conventional solutions disadvantageously do not or only inadequately satisfy the many economic aspects for recovering the pure chaff fraction.
It is desirable since some time to use the chaff having high energy content—in addition to the straw and the grain—as biomass. The by about 50% lower nitrogen content of the chaff compared to that of the grain results in reduced nitrogen emission during combustion. In addition, the chaff has a lower potassium and chlorine content than straw, which results in reduced particle emissions and reduced slag formation in the ash. It should also be mentioned in this context that the chaff is suitable both as bedding due to its high absorption capability and as a feed additive due to its high feed value.